DE2948287A1 - CIRCUIT ARRANGEMENT FOR HIGH INTENSITY DISCHARGE LAMPS - Google Patents

Description

Background of the invention

The invention relates to ballast for high-intensity discharge lamps and in particular to a direct drive ballast circuit a lamp starting circuit and a de-energizing circuit for them for using a high-intensity discharge lamp.

In general, high intensity discharge lamps, such as mercury arc lamps or sodium vapor lamps, for example, have negative resistance with a sustaining voltage that is a function of the arc tube temperature. A choke is therefore usually used as a ballast to control the flow of current with reference to the voltage of the Limit lamp. The result, however, is that the power available on the lamp is limited and that the warm-up period occurs before the desired lighting is achieved relatively long 1st. Throttle upstream devices also have a relatively poor efficiency, are heavy and space-consuming to an undesirable extent and are exposed to poor power regulation as soon as voltage fluctuations occur in the network.

Attempts to eliminate these drawbacks have led to the development of electronic ballast circuits such as wake-up choke converters (ringing-choke converter), push-pull inverters, and switching regulators. The wake-up converter, however, tends to suffer from poor operating efficiency, while the push-pull inverter tends to suffer from relatively poor regulation and an excess of magnetic components plagued 1st. The switching regulator therefore seems to be best suited for ballast applications.

Circuit arrangements of the type of switching regulator are and will be used in connection with high intensity discharge lamps, it was however, it was found that the currently known circuits leave something to be desired. More precisely, it was found that the well-known

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Circuit arrangements of the switching regulator type for high-intensity arc lamps are relatively expensive in terms of components and assembly costs, while in terms of efficiency and energy consumption Keep your wishes open.

Summary of the invention

According to one aspect of the invention, an improved electronic Direct drive ballast circuit for high-intensity discharge lamps a high frequency inverter circuit connected to a DC power source coupled by a charge storage and isolation circuit is bridged, and with a load circuit, the one Contains high intensity discharge lamp. A starting circuit for the High frequency inverter couples the direct current source to the high frequency inverter and becomes inactive after energizing the high-frequency inverter. A lamp start or preparation circuit is also provided by the Start-up circuit for the high-frequency inverter is activated and takes care of the development of a voltage sufficient for the high-intensity discharge lamp to excite, whereupon a de-excitation circuit is provided that, in response to the conduction of the high intensity discharge lamp causes the lamp start or preparation circuit to trip.

The invention and other objects, advantages and possibilities of the same are explained in more detail in connection with the drawing; show it:

Figure 1 is a block diagram of a preferred embodiment of a Direct drive ballast circuit for a high-intensity discharge lamp and

Figure 2 is a circuit diagram of a preferred direct drive ballast shell device according to Figure 1.

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According to the block diagram of FIG. 1, there is an alternating voltage source connected to a line conditioning circuit 5 with a rectifier 7. The rectifier 7 is provided with a high frequency inverter circuit 9, which in turn is connected to a load circuit 11. The load circuit 11 is provided with an inverter drive circuit 13 coupled to load-dependent driving voltages for the High frequency inverter circuit 9 and a feedback rectifier circuit 15 to get. The feedback rectifier circuit 15 provides load-dependent energy for a charge storage unit Isolation circuit 17 which bridges the rectifier 7.

A direct drive start circuit 19 for the high frequency inverter circuit 9 is coupled to this and to the rectifier 7 and the charge storage and isolation circuit 17. Furthermore, there is a high-intensity discharge lamp starting circuit 21 with the feedback rectifier circuit 15 coupled to the charge storage and isolation circuit 17 and to a potential reference level or Circuit ground. In addition, a trigger circuit 23 is for the lamp starting circuit 21 is coupled to the load circuit 11 and bypasses the lamp starting circuit 21.

Figure 2 shows a special embodiment of the direct drive shell Device circuits according to FIG. 1 and the reference numerals of the figure can be used for the components according to FIG. The line conditioning circuit 5 here has an overload switch 25 with a Side of an alternating voltage source 3 is connected as well as with one side a first choke 27. The other side of the alternating voltage source is connected to one side of a second throttle 29. Both chokes 25 and 27 are preferably attached to the same core to the mutual To maximize inductance between these chokes and the far sides are coupled with a capacitor 31.

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The rectifier 7 is constructed as a Graetz circuit. He knows two diodes 33 and 35 connected to one side of the line conditioning circuit 5 and two diodes 37 and 39 connected to the other side of the line conditioner. A filter capacitor 41 and a Zener diode 43 are connected in parallel across the series connection of diodes 33 and 35 and the series connection of diodes 37 and 39.

The high-frequency inverter circuit 9 is connected to the rectifier 7. The high frequency inverter circuit 9 has two in series switched transistors 45 and 47, which bridge the rectifier 7. The connection 49 of the series connection of transistors 45 and 47 is coupled to a series resonant circuit comprising a series-connected capacitor 51, a primary winding 53 of a second transformer 55 and a secondary winding 57 of a third transformer 59 of the feedback rectifier circuit 15 contains. The base and emitter of the two series transistors 45 and 47 are connected to a drive winding 61 or 63 of a first transformer 65 coupled, with a damping resistor 67 or 69 bridging the drive windings 61 and 63.

To the high frequency inverter circuit 9 is a high frequency inverter drive circuit 13 arv coupled. This high frequency inverter drive circuit 13 has a primary winding 71 of the first transformer 65, so that the secondary windings 61 and 63 and the transistors 45 and 47 get excited. The excitation of the high frequency inverter circuit 9 hangs So from the current flow through the inverter drive circuit 13, which in turn coupled to the load circuit 11 and from the flow of current in this is dependent.

The load circuit 11 includes a secondary winding 73 of the second Transformer 55 in series with the primary winding 75 of the third transformer 59 of the feedback rectifier circuit 15, a load capacitor 77 and an unillustrated high intensity discharge lamp. In addition, the second winding 73 is also in

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Connected in series with the primary winding 71 of the high frequency inverter drive circuit 13.

As mentioned above, the feedback rectifier circuit 15 has in the form of a voltage doubler, the secondary winding 57 of the third transformer 59 on. This secondary winding 57 is coupled to a capacitor 79 with the connection of two 1n series-connected diodes 81 and 83, so that a voltage doubler circuit is formed. One of the series-connected diodes 83 is with the Connection point of a series capacitor 85, which is bridged by a resistor 87 and an isolating diode 89 of the charge storage and isolation circuit 17, connected.

A direct drive start circuit 19 for the high-frequency inverter circuit 9 has a resistor 91 and a diac 93, which is connected in series with the rectifier 7 and the connection of capacitor 85 and diode 89 of the charge storage and isolation circuit 17. The connection point of the series resistor 91 and the diac 93 is coupled to the base of the transistor 47 of the high-frequency inverter circuit 9 by means of a series resistor / una capacitor 97.

Furthermore, a lamp starting circuit 21 in the form of a relaxation oscillator has a diac 99 which is connected to the connection point of the series capacitor 85 and the diode 89 of the charge storage and isolation circuit 17 and the diac 93 of the direct drive starting circuit 19. T _he diac 99 is connected via a first series resistor 101, capacitor 103 and a second resistor 105 to circuit ground. The connection of series capacitor 103 and second resistor 105 is connected to the base of a first transistor 107, the emitter of which is coupled via a resistor 109 to circuit ground and directly to the base of a second transistor 111 with a grounded emitter. The collector of the first transistor 107 is connected to the collector of the second transistor 111 and via a

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Diode 113 with the feedback rectifier circuit 15. Der The connection point of the first resistor 101 and the capacitor 103 is also connected to a resistor 114 which is connected to the Connection point of a resistor 115 is coupled, which is connected to diac 99 and a transistor 117, in turn is connected to circuit ground. The collector of a further transistor 119 is connected to the base of transistor 117 and via a resistor 121 to the diac 99. The emitter of the transistor 119 is connected to a voltage reference level, for example circuit earth.

In addition, a trigger circuit 23 for the lamp starting circuit 21 has a fourth transformer 123 which has a primary winding 125 which is connected to the capacitor 77 and the high-intensity discharge lamp (not shown) of the load circuit 15. The secondary winding 127 of the fourth transformer has a center tap connected to a reference potential and opposite ends each connected to a diode 129 and 131 are connected. The diodes 129 and 131 are commonly connected to a resistor 133 and via a filter capacitor 135 with the potential reference level. The resistor 133 is coupled to the base of the transistor 119 and via a resistor 121 to the Potential reference level.

In operation, a voltage from the AC voltage source 3 is also used the line conditioning circuit 5 filtered, which serves as a filter for both short voltage surges and high-frequency interference. That resulting filtered AC signal that is free of unwanted transient spikes and high frequency signals is applied to the Graetz rectifier circuit 7 is applied. The rectifier circuit 7 supplies a pulsating DC voltage with a frequency of about 120 Hz. In addition, this pulsating DC voltage is changed, as will be explained in more detail below, to a relatively constant one DC voltage to be sent to the high frequency inverter circuit is placed.

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The high frequency inverter circuit 9 is in the form of a chopper with two substantially similar transistors 45 and 47 which can operate in push-pull operation. The oscillator or inverter 9 has a series resonance output circuit including the capacitor 51 and the primary winding 53 of the second transformer 55. This Series resonant circuit has a resonant frequency of about 20 kHz, what is well above the audible range and is therefore removed from frequency ranges that can be unfavorable or annoying for a user. As expected, this series resonance output circuit provides one Path of low impedance for current flowing through it and any increase in the current flow of an increased current flow in the secondary windings 73 of the second transformer 55 as well as a higher current flow in the primary winding 71 of the first transformer 65, the Primary winding 75 of the third transformer 59 and the primary winding 125 of the fourth transformer 123 are accompanied.

It is important that increased current flow in the secondary winding 73 of the second transformer 55, or the load circuit 11, of higher Current flow in the primary winding 71 of the transformer 65 or the inverter drive circuit 13 is accompanied. The high-frequency inverter circuit 9 therefore not only derives drive voltage from the series resonant circuit with capacitor 51 and inductor winding 53, but also in accordance with the magnitude of the current which flows in load circuit 11.

Increased current flow in the resonant circuit with winding 53 of the second transformer 55 is also accompanied by a higher current flow in the inductive windings 75 and 57 of the third transformer 59. This higher Current flow is through the voltage doubler with the diodes 81 and 83 are rectified and applied to the charge storage capacitor 85. The charge storage capacitor 85 stores these received Energy as long as the pulsating DC voltage of the rectifier 7 remains above a given reference level. However, if the pulsating DC voltage falls below the given reference level, the

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Capacitor energy through the isolating diode 89. So it stands a relatively constant DC voltage across the high frequency inverter circuit.

It was also determined that the switching capability of the transistors a high frequency inverter circuit is improved if it is directly driven by a transformer rather than a complex base bias arrangement. However, it was also found that the high frequency inverter circuit 9 does not start by itself when a direct drive system has been used. It was also found that that minimizing the number of components in the starting circuit would reduce costs that would facilitate mechanized assembly and would increase the reliability of the circuit.

Regarding the operation of the starting circuit 19 for the high frequency inverter 9 it should be noted that initially there is no energy feedback to the charge storage capacitor 85 is present before the high frequency inverter circuit 9 works. The energy from the AC voltage source 3, however, ensures the development of a relatively high potential on capacitor 41, which in turn results in the development of a relatively high potential on capacitor 97 of the inverter start circuit 19 Across resistors 91 and 95 and winding 63 of the first Transformer 65 causes. Furthermore, the high-frequency inverter 9 is not yet in operation.

When the charge appearing on capacitor 97 is the breakdown voltage of the diac 93 exceeds, the capacitor 97 discharges through the diac 93, the capacitor 85 and the winding 63 of the first transformer The winding 63 transfers the discharge current to the emitter-base junction of the transistor 47 of the high-frequency inverter circuit 9, so that the transistor is biased into the conductive state and the oscillator of the high frequency inverter circuit 9 is started. After starting, the high-frequency inverter circuit 9 loads the memory

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capacitor 85. This charge on the storage capacitor 85 is sufficient off to prevent the voltage across the isolating diode 89 from generating a To achieve a value that is sufficient to cause the diac 99 to break down. As a result, the starting circuit 19 is practically off Operating circuit removed once the task of starting the high-frequency inverter circuit 9 has been completed.

Furthermore, it is well known that high-intensity discharge lamps need a starting voltage that is greater than the voltages that are required to keep the lamp running. It therefore becomes necessary to create a lamp starting voltage that is so high how 2.5 kV can be achieved using high intensity discharge lamps.

For this purpose, a rise in the voltage across the storage capacitor 85 causes the diac 99 to break down, whereupon a pulse voltage is generated is placed at the capacitor 103 to the base of the transistor 107, so that this becomes leading. The transistor 107 in turn ensures conductivity of the transistor 111 and the diode 113, whereupon the feedback rectifier circuit 15 is practically short-circuited and the high-frequency inverter circuit 9 is driven harder. When the high frequency inverter 9 is driven harder, the current flow increases 1n the Load circuit 11 and the secondary winding 73 of the second transformer 55, the winding 75 of the third transformer 59 and the capacitor 77, which form a series resonance circuit. A charge is then sent to the Capacitor 77 1n of sufficient height is formed to "ignite" the high-intensity discharge lamp in load circuit 11 or its line initiate.

Furthermore, ignition of the high-intensity discharge lamp (not shown) causes a higher current to flow through the winding 125 of the fourth Transformer 123. This higher current flow is through winding 127

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ORIGINAL INSPECTED

coupled to diodes 129 and 131 to obtain a rectified voltage which is filtered and to transistor 119 is placed and makes it conductive. The transistor 117 in turn is not conductive, so that practically the lamp starting circuit 21 is removed from the operating circuit. The lamp start circuit 21 therefore causes the high-intensity discharge lamp to "ignite" and is practically disconnected from the circuit as soon as the high intensity arc lamp reaches a conductive state.

So it is a unique electronic direct drive ballast circuit made available for high intensity discharge lamps been. The circuit has improved starting capability and the ballast starting circuit is made virtually inoperative once the high frequency inverter circuit becomes operational. It is also provided a unique lamp start circuit in which the The high voltages required to "ignite" a high-intensity discharge lamp are required to be derived from the high-frequency inverter arrangement. In addition, there is a trigger circuit provided so that the lamp starting circuit practically from the active, operational circuit is taken out when the high-intensity discharge lamp is excited. In addition, the circuit is load-dependent, so that changes in the load conditions are immediately reflected in the direct drive shell device circuitry and control their operation.

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Claims (11)

294Θ287 S6 P183 D claims 1. Circuit arrangement for direct drive ballasts for a High intensity discharge lamp, with a high frequency inverter circuit, which is connected to a DC power source, a charge storage and isolation circuit, which is the DC power source bridged, a high-frequency inverter starting circuit that works with the DC power source and the charge storage and isolation circuit and coupled to the high-frequency inverter circuit, characterized in that that a high intensity discharge lamp load circuit is coupled to the high frequency inverter circuit, wherein a high frequency inverter drive circuit the high intensity discharge lamp load circuit to the high frequency inverter circuit, a feedback rectifier circuit couples the high intensity discharge lamp load circuit couples with the charge storage and isolation circuit, a lamp start circuit with the Charge storage and isolation circuit and the feedback rectifier circuit is coupled, and a lamp trip circuit with the high-intensity discharge lamp load switch and the lamp start switch is coupled so that the lamp start circuit changes the feedback rectifier circuit in such a way that the High-frequency inverter circuit is caused to load the high-intensity discharge lamp circuit to excite in sufficient amount to excite the high-intensity discharge lamp, and the excitation of the High intensity discharge lamp causes the lamp trip circuit the lamp start circuit switches off. 2. Circuit arrangement according to claim 1, characterized in that one Line conditioning circuit between the DC power source and an AC power source. ..JM 030Q33 / 0B28 ORIGINAL INSPECTED 3. Circuit arrangement according to claim 1 or 2, characterized in that the lamp starting circuit has the form of an oscillator circuit device. 4. Circuit arrangement according to claim 3, characterized in that the oscillator circuit is between the charge storage and isolation circuit and the feedback rectifier circuit. 5. Circuit arrangement according to claim 4, characterized in that that the oscillator circuit is in series with a first switch circuit which is the feedback rectifier circuit bridged. 6. Circuit arrangement according to claim 5, characterized in that the oscillator circuit has a series connection of diac and capacitor. 7. Circuit arrangement according to one of claims 1 to 6, characterized in that the lamp trigger circuit contains a rectifier device which is coupled to the high-intensity discharge lamp load circuit and via a filter and a second Switching device with the lamp start circuit. 8. Circuit arrangement according to one of claims 1 to 7, characterized in that the high-intensity discharge lamp load circuit contains a series circuit of inductance and capacitance, which form a series resonant circuit which is coupled to a high-intensity discharge lamp. 9. Circuit arrangement according to one of claims 1 to 8, characterized in that the feedback rectifier circuit has a Transformer winding in series with a series resonance circuit and a high-intensity discharge lamp of the high-intensity discharge lamp load circuit contains. ... / A3 030033/0528 10. Circuit arrangement according to one of claims 1 to 9, characterized characterized in that the feedback rectifier circuit includes a voltage doubler rectifier which the High intensity discharge lamp load circuit connects to the charge storage and isolation circuit. 11. Circuit arrangement according to one of claims 1 to 10, characterized characterized in that the feedback rectifier circuit takes the form of a double diode rectifier coupled to the high intensity discharge lamp load circuit and via a second switching device to the lamp starting circuit. 030033/0528